package com.uam.core.lk.utils.id;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * 
 * @ClassName:  IdWorker   
 * @Description:全局唯一的id生成器  
 * @author: zhangxj
 * @date:   2018年12月24日 下午5:27:49   
 *     
 * @Copyright: 2018 www.luokung.com Inc. All rights reserved. 
 * 注意：本内容仅限于箩筐科技内部传阅，禁止外泄以及用于其他的商业目
 */
public final class IdWorker {
	private static final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMddHHmmss");
	private long workerId;
	private long datacenterId;
	private long sequence = 0L;

	private long twepoch = 1288834974657L;

	private long workerIdBits = 5L;
	private long datacenterIdBits = 5L;
	private long maxWorkerId = -1L ^ (-1L << workerIdBits);
	private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits);
	private long sequenceBits = 12L;

	private long workerIdShift = sequenceBits;
	private long datacenterIdShift = sequenceBits + workerIdBits;
	private long timestampLeftShift = sequenceBits + workerIdBits
			+ datacenterIdBits;
	private long sequenceMask = -1L ^ (-1L << sequenceBits);

	private long lastTimestamp = -1L;

	public IdWorker(long workerId, long datacenterId) {
		// sanity check for workerId
		if (workerId > maxWorkerId || workerId < 0) {
			throw new IllegalArgumentException(String.format(
					"worker Id can't be greater than %d or less than 0",
					maxWorkerId));
		}
		if (datacenterId > maxDatacenterId || datacenterId < 0) {
			throw new IllegalArgumentException(String.format(
					"datacenter Id can't be greater than %d or less than 0",
					maxDatacenterId));
		}
		this.workerId = workerId;
		this.datacenterId = datacenterId;
	}

	/**
	 * 32位唯一ID
	 * @return
	 */
	public synchronized String nextLongId() {
		String genId = String.valueOf(genId());
		return dateFormat.format(new Date()) + genId.substring(genId.length() - 18, genId.length());
	}
	/**
	 * 21位唯一ID
	 * @return
	 */
	public synchronized String nextShortId() {
		String genId = String.valueOf(genId());
		return dateFormat.format(new Date()) + genId.substring(genId.length() - 6, genId.length());
	}
	/**
	 * 18位唯一ID
	 * @return
	 */
	public synchronized String nextOrderId() {
		return String.valueOf(genId());
	}
	
	private long genId() {
		long timestamp = timeGen();
		if (timestamp < lastTimestamp) {
			throw new RuntimeException(
					String.format(
							"Clock moved backwards.  Refusing to generate id for %d milliseconds",
							lastTimestamp - timestamp));
		}

		if (lastTimestamp == timestamp) {
			sequence = (sequence + 1) & sequenceMask;
			if (sequence == 0) {
				timestamp = tilNextMillis(lastTimestamp);
			}
		} else {
			sequence = 0L;
		}

		lastTimestamp = timestamp;
		
		return ((timestamp - twepoch) << timestampLeftShift)
				| (datacenterId << datacenterIdShift)
				| (workerId << workerIdShift) | sequence;
	}

	protected long tilNextMillis(long lastTimestamp) {
		long timestamp = timeGen();
		while (timestamp <= lastTimestamp) {
			timestamp = timeGen();
		}
		return timestamp;
	}

	protected long timeGen() {
		return System.currentTimeMillis();
	}
	
	public static void main(String[] args) {
		final IdWorker idWorker1 = new IdWorker(0, 3);
		System.out.println(idWorker1.nextShortId());
		final IdWorker idWorker2 = new IdWorker(1, 0);
		
		for(int i = 0; i < 200; i++) {
			String id = idWorker1.nextShortId();
//			String orderId = idWorker2.nextOrderId();

			System.out.println(idWorker1.nextShortId());
//			System.out.println(idWorker2.nextShortId());
		}
	}
}